Optical fibers have been used widely for many applications, most notably for optical fiber communication. As the optical fiber communication is inching toward individual offices and residential area, the cost of optical fiber interconnection becomes the major issue. The optical fiber interconnection includes fiber-to-fiber connection, fiber-to-light source connection, fiber-to-detector connection, and an optical fiber to other optical components. The interconnection costs are high due to the small size of the optical beams involved. A typical laser diode has a light-emitting spot in the order of one or two microns. Single-mode fiber, the most commonly used one, has about 9-micron core (and 125 micron cladding). When two single-mode fibers, or a single-mode fiber and a laser diode, are connected, the alignment should be within one or two micron in terms of the transverse offset.
In an conventional connector, in order to achieve such an alignment accuracy when connecting two optical fibers, each of the fibers is inserted in an elongated precision plug with nominally 125 micron inside diameter (ID). The two mating plugs are then inserted into an elongated precision sleeve. The required tight dimensional requirements of these elongated parts drive up the cost of the optical fiber connection.
The difficulty escalates quickly when the number of optical fibers increases in so-called array interconnection. Surface emitting laser diodes and detectors are produced in a two-dimensional array on a semiconductor wafer. The positional accuracy of these optical components while on the wafers is better than one micron as they are registered by photolithographic method. However, such a precision has not been achieved in the conventional array connectors for optical fibers, while there are increasing requirement for a large array interconnection for local area network, optical data processing, and optical computing.